HABITAT: Where an organism lives
HALF LIFE: The time required for half of any given amount of a radioactive substance (parent atoms) to decay into another substance (daughter atoms)
HALOGENS: Group 7A. Nonmetals. 7 valence electrons. VERY high reactivity.
HAPLOID (1N): Cells that only contain half the total number of chromosomes. These cells are made during meiosis. Most haploid cells are gametes or sex cells.
HERBIVORE: An organism that only consumes plants.
HEREDITY: The passing of traits from parents to offspring. This is one of the five characteristics of life.
HETEROGENEOUS MIXTURE: A mixture that is not the same throughout. For example, oil and vinegar.
HETEROTROPH: An organism that has to eat or absorb other living things to get food. These organisms must participate in cellular respiration to unlock the stored energy in the food they consume.
HETEROZYGOUS: In genetics, an organism is heterozygous for a trait if it has one dominant allele and one recessive allele. Example: Bb.
HOMEOSTASIS: Keeping your insides in balance; maintaining a stable internal environment. This is one of the five characteristics of life.
HOMOGENEOUS MIXTURE: A mixture that is the same throughout. You cannot see the separate parts of the mixture. For example, saltwater.
HOMOLOGOUS: Similar
HOMOLOGOUS CHROMOSOMES: Chromosomes that are the same size, shape and control the same function. You receive one from mom and the other from dad.
HOMOLOGOUS STRUCTURES: Structures with common evolutionary origin; provides evidence of evolution from a common ancestor. Example: forelimb of a crocodile, whale and cat all contain similar bone structure
HOMOZYGOUS: In genetics, an organism is homozygous for a trait if it has two alleles that are the SAME. Example: BB or bb genotypes.
HOMOZYGOUS DOMINANT: An organism that has two capital alleles for their genotype. Example: HH
HOMOZYGOUS RECESSIVE: An organism that has two lowercase alleles for their genotype. Example: hh
HOOKE, Robert: The first scientist to observe cells. He came up with the word "cell" because the small structures reminded him of rooms.
HUNTINGTONS DISEASE: A dominant genetic disorder that causes holes to develop in the brain. This is the only dominant disorder discussed in class.
HYDROTHERMAL VENT: An ecosystem located in the aphotic zone of the ocean. Cracks in the earth's crust release chemicals that special bacteria use for chemosynthesis. Example of organisms that live here include tube worms, octopus, vent fish, giant white clams, etc.
HYPOTHESIS: An educated guess or prediction.